WO2004079715A1 - Pick-up comprising at least one piezo sensor for musical instruments and use thereof - Google Patents

Abstract

The invention relates to a pick-up comprising at least one piezo sensor for musical instruments with a resonant body wall that is capable of vibrating, particularly for string and percussion instruments. The pick-up (TA1) comprises at least one piezo sensor (15) and is fastened with vibration-transmitting contact to the resonant body wall (4), preferably on the inner surface thereof so that it cannot be seen from the exterior. The piezo signals of the piezo sensor (15) can be amplified by an active transistor wiring (16), which is connected thereto, while transforming impedance. In acoustic guitars, the pick-up (TA1) is coupled in a vibration-transmitting manner to the soundboard (4) of the guitar. When combining this soundboard pick-up (TA1) with a bridge pick-up (TA2), the mixing of both signals results in a frequency band that is very natural. The invention also relates to the use of piezo-ceramic sensors, piezo-film sensors, piezo-polymer sensors or back-electret sensors for the piezo sensor (15).

Description

Pickups with at least one piezo sensor for musical instruments and use

The invention relates to a pickup for musical instruments with at least one resonable body wall capable of oscillation, in particular for string and percussion instruments, according to the preamble of claim 1.

A number of requirements are placed on such pickups: reproduction of the recorded sound spectrum that is as lifelike as possible; small size and easy to assemble so that it can be mounted on the string or percussion instrument as inconspicuously as possible; good manufacturability; Immunity to interference and good shielding, i.e. no negative influence from interference fields, to name only the most important.

The invention has for its object to provide a pickup of the type mentioned, with which the above requirements are met in a particularly inexpensive manner and with which it is also possible to use the frequency spectrum supplied by piezoelectric bridge pickups to add that a surprisingly lifelike sound can be achieved even at high volumes (music playback in halls).

According to the invention the object is achieved by the features specified in the characterizing part of claim 1, namely in that the pickup has at least one piezo sensor and is attached to the resonance body wall - preferably not visible on the inside from the outside - in vibration-transmitting contact and that Piezo signals of the piezo sensor can be amplified by at least one active transistor circuit connected to them with impedance conversion. Advantageous further developments are given in claims 2 to 16. According to the

Use according to claim 17 advantageously uses piezo-ceramic sensors, piezo-film sensors, piezo-polymer sensors or back-electret sensors for the piezo sensor.

The advantages that can be achieved with the invention are to be seen above all in that the combination of the piezo sensor with the active (ie connected to a voltage source) transistor circuitry brings about an impedance conversion from the high-resistance internal resistance of the sensor into the relatively low-resistance output of the transistor circuit becomes. This in turn has advantages in terms of insensitivity to magnetic stray fields and feedback phenomena and the possibility of longer connecting lines. This means that the shielding of the signal lines is useful, but not nearly as critical. table and necessary as with high-resistance circuits. The size of the series resistor in the transistor circuit can be used to bring about a bass boost or weakening to a certain extent, ie a desired basic setting.

The pickup according to the invention finds a preferred application in acoustic guitars and is coupled to the ceiling of the guitar in a vibration-transmitting manner, preferably invisibly on the inside of the ceiling. It has been found that the structure-borne noise spectrum obtained in this way results in a particularly “warm” sound, which can surprisingly be mixed well with the frequency spectrum of a piezoelectric bridge tone absorber on the same guitar, which is particularly noticeable at high volumes (natural sound without overdriving). Accordingly, it is provided according to a preferred embodiment that the piezo signals of the “ceiling” pickup (first piezo signals) are mixed with those (second piezo signals) of a so-called bridge pickup, ie a piezo pickup, which is integrated in the guitar bridge and whose signals are formed on the basis of the forces exerted on it by the strings via pressure pieces, the first and second piezo signals preferably being able to be preamplified by a preamplifier and in a downstream one Guitar amplifiers or a mixer with selectable weighting of the two sound components are mixable.

There are ways of playing the guitar in which the ceiling is hit with the ball of the hand or fingers to emphasize the rhythm. The pickup according to the invention is also particularly suitable for the true-to-life transmission of such percussion effects. A side effect is that you can switch on electronic rhythm synthesizers with a beat signal from the ceiling pickup, which is supplied by the ceiling pick-up and amplified accordingly, even over longer distances in a clock-synchronized manner.

Further features and advantages as well as the structure and function of the subject matter of the invention are explained in more detail below on the basis of exemplary embodiments shown in the drawing. In the drawing shows in part. schematic, simplified representation:

Figure 1 is an acoustic guitar with a ceiling pickup according to the invention and with a piezoelectric bridge pickup, in a perspective view. 2 shows an embodiment of a pickup with an elongated piezo ceramic without a housing and with a partially removed shielding film and with a protruding end of the circuit board for transistor wiring, in plan view; Fig. 3 the elevation belonging to FIG. 2 with the housing lower part shown transparently; 4 shows a section along the plane rV-rV from FIG. 3, additionally with double-sided adhesive tape glued to the underside of the lower housing part; FIG. 5 shows the object according to FIG. 4, enlarged and provided with an upper housing part; and FIG. 6 shows a modification of the pickup according to FIGS. 2 to 5 with a circular basic shape, in plan view.

In Fig. 1 means 1 the sound body or body of a concert or acoustic guitar, 2 its bottom, 3 the frame, 4 the ceiling, 5 the sound hole, 6 the bridge board, 7 the neck with fingerboard, 8 each a fret, 9 the Bundstäbchen, 10 the head, 11 the vertebrae and 12 the saddle. The bridge board has an anchor board 6.1 firmly connected to it, on which the strings 13 are fixed at one end. The other ends of the strings are drawn through holes (not visible) in the tensioning shafts 1a, so that the individual strings 13 are tensioned or loosened by actuating the pegs 11 and the guitar can thus be tuned. The bridge board 6 glued to the ceiling 4 has a string-transverse receiving groove 6a, into which a bridge pickup TA2, not shown, is inserted. 14 is a plug socket fastened in the lower frame area, into which the plug of the shielded cable of an amplifier can be inserted. The pickup TAl according to the invention, which will be discussed in more detail, is attached to the underside of the ceiling 4 in vibration-transmitting contact with it, in particular glued on. A shielded signal line L1, L2 leads to a preamplifier VV fastened in a receiving opening of the frame 3. With the preamplifier W you can use sliders or rotary knobs to influence the two tone signals of the pickups TAl, TA2 separately, e.g. regarding volume, brilliance, treble, contour, frequency. The preamplifier W supplies the preamplified audio signals to the two-channel and therefore at least three-pole plug socket 14 via two separate signal lines or a two-channel signal line (not shown), so that the optimal mixing of the two audio signals can be produced in a downstream two-channel guitar amplifier.

The pickup TAl, which is shown in more detail in FIGS. 2 to 5, is intended for musical instruments with at least one resonable body wall capable of oscillation, in particular for string and percussion instruments. The pickup TAl has at least one piezo sensor 15 and is attached to the resonance body wall (in the example the ceiling 4 of the guitar according to Fig.l) - preferably not visible from the outside on the inside - in vibration-transmitting contact. The piezo signals of the piezo sensor 15 can be amplified by at least one active transistor circuit 16 connected to them. From FIGS. 2 to 5 it can be seen that if the piezoceramic body 15 is rectangularly elongated, it is insulated ( Insulating strips 17) of its neutral flanks 15a, 15b, together with a board 18 assigned to them, are surrounded by a shielding jacket 19, consisting of a highly conductive metal foil connected to the ground potential, a wiring section 18a of the board 18 protruding from the shielding jacket 19 which the at least one transistor 16T and a bleeder resistor 16W are arranged and connected to the signal output 20 of the piezoceramic 15 on the one hand and to the ground potential on the one hand, with the transistor 16T amplifying the piezo signal and supplying it to a signal output 22 ,

The transistor 16T and its circuitry 16, e.g. the leakage resistor 16W between the piezo signal contact 20 and ground potential 21 of the circuit board 18 can also be designed as integrated components instead of the discrete switching elements.

4 and 5 show more clearly, the ceramic body 15 of the piezo sensor is seated with its base 15c on the contact surface 18b of a conductor track of the circuit board 18, which extends according to FIG. 2 with a wiring section 18a in the longitudinal direction over the ceramic body 15 is. The two side flanks 15a, 15b of the ceramic body 15 are covered by insulating strips 17, and the metallic shielding foil 19, in particular a copper foil, is wrapped or wrapped around the outer lateral surfaces of the ceramic body 15 and the circuit board 18. The ground contact 21 or the ground potential is thus formed by the shielding film 19 and the U-shaped housing parts 22U (lower part) and 220 (upper part) contacting it, the gap 23 between (22U) and (220) being able to be closed by soft soldering. For this purpose, the two housing parts 22U, 220 consist of a solderable metal or a corresponding metal alloy, e.g. German silver.

A JFET transistor is advantageously arranged on the wiring section 18a of the circuit board 18. Its gate connection G is connected to the piezo signal contact 20, its drain connection D to the signal output and its source connection S to ground. The transistor 16T is arranged in a floating manner in a silicone bed 24, and for this purpose its ground line S and its signal output line D are provided with elastic deflection. possible shape and excess length. The aforementioned two connecting lines D and S of the transistor 16T are (see in particular FIG. 2) bent in a wave shape so that they have enough play to effect a vibration decoupling together with the silicon bed 24, specifically in relation to those directly connected to the piezo signal. Contact connected terminal G of the transistor 16T and the transistor itself. The transistor 16T receives its supply voltage from the preamplifier VV (not shown in detail).

An advantageous attachment of the pickup TAl on the guitar ceiling 4 (Fig. 1) or generally on the soundboard wall is by means of double-sided tape (Fig. 4 and 5). That a piece of the adhesive tape corresponding to the base area of the pickup TAl is adhered to the underside of the lower housing part 22U by (TAl), then the pickup is pressed with the free side of the adhesive tape 25 against the fastening point and thus adhered. The adhesive material has e.g. an elastically deformable acrylic adhesive has proven to be advantageous.

6, the pickup has a round or elliptical basic shape, and accordingly the piezo sensor, the insulating strips for its flanks, the metal foil, the circuit board 18 with its protruding wiring section as well as the lower and upper parts of the housing are attached to the adapted circular or elliptical floor plan, which is not shown in detail, but results analogously in a modification of the cuboid shape according to FIGS. 2 to 5 into a disk shape. The following are particularly suitable as materials for the piezo sensor 15: ceramic sensors,

Piezo film sensors, piezo polymer sensors or back electret sensors.

As already explained with reference to Fig. 1, a particular advantage of the pickup TAl, TAT is that its piezo signals (first piezo signals) are mixed with those (second piezo signals) of a so-called bridge pickup TA2, i.e. a piezo pickup, which is integrated into the guitar bridge and whose signals are formed on the basis of the forces exerted on it by the strings via pressure pieces, the first and second piezo signals preferably being able to be preamplified by a preamplifier or a two-channel preamplifier W and can be mixed in a downstream guitar amplifier or a mixing device with selectable weighting of the two sound components. This advantage can also be realized if the pickup is placed on the ceiling of a

String instrument, e.g. B. in the form of violin, viola, cello or double bass, is coupled to transmit vibrations and these instruments also have a bridge pickup. point, but the ceiling pickup is a surprisingly natural one

Sound results.

Accordingly, the pickup can also be connected to the resonance wall of a piano or grand piano in a vibration-transmitting manner or to the ceiling of another stringed instrument, e.g. B. in the form of banjo, balalaika or mandolin, coupled to transmit vibrations.

LIST OF REFERENCE NUMBERS

1 sound body or body

2 bottom of (1)

3 frame

4 blanket

5 sound hole

6 footboards

7 neck

8 fret

9 bundle sticks

10 head

11 vertebrae

12 saddle

6.1 anchor board

13 strings

11a tension shafts

6a receiving groove

TA2 bridge pickup

14 plug socket

TAl ceiling cartridge

LL1, L2 signal lines, shielded

W preamplifier

15 piezo sensor

16 transistor circuit

17 insulating strips

15a, 15b neutral edges of (15) 18 board

19 shielding jacket

18a wiring section of (18)

16T transistor

16W leakage resistance

20 signal output from (15)

22 signal output from (16)

21 ground potential

15c footprint of (15)

18b contact surface

22U, 22O lower and upper part of the housing

23 gap between (22U) and (220)

G gate connector

D drain connector

S source connector

24 silicone bed

25 double-sided adhesive tape

TAl 'cartridge, another

Claims

claims Pickup for musical instruments with at least one vibrating resonance body wall, in particular for string and percussion instruments, characterized in that the pickup (TAl) has at least one piezo sensor (15) and on the resonance body wall (4) - preferably on the inside not visible from the outside - is fixed in vibration-transmitting contact and that the piezo signals of the piezo sensor (15) can be amplified by at least one active transistor circuit (16) connected to the latter with impedance conversion. 2. Pickup according to claim 1, preferably for acoustic guitars, characterized ge z e i chn et that the pickup (TAl) on the ceiling (4) of the guitar is coupled to transmit vibrations. 3. Pickup according to claim 2, characterized in that its piezo signals (first piezo signals) are mixed with those (second piezo signals) of a so-called bridge pickup (TA2), i.e. a piezo pickup which is integrated in the guitar bridge (6) and whose signals are formed on the basis of the forces exerted on it by the strings (13) via pressure pieces, the first and second piezo signals preferably being each provided by a preamplifier (W) can be pre-amplified and mixed in a downstream guitar amplifier or a mixer with selectable weighting of the two sound components. 4. Pickup according to one of claims 1 to 3, d adurch gekennz ei chn et that that with a rectangular-elongated shape of a piezoceramic body (15) this with isolation of its neutral flanks (15a, 15b) together with a circuit board assigned to it (18) are surrounded by a shielding jacket (19) consisting of highly conductive metal foil connected to the ground potential, a shielding section (18a) of the circuit board (18) protruding from the shielding jacket (19), on which the at least one transistor ( 16T) and a leakage resistor (16W) are arranged and each are connected with one pole to the signal output (20) of the piezoceramic (15) and to the ground potential (21), the transistor (16T) connecting the piezo Signal amplified and fed to a signal output (22). 5. Pickup according to claim 4, characterized ^~ gekennz ei chn et that the Transist (16T) and its wiring, such as the bleeder resistor (16W) between the piezo-signal contact (20) and ground potential of the circuit board (18) , are designed as integrated components. 6. Pickup according to one of claims 1 to 5, characterized g eken nzei chn et that a Keramikköφer of the piezo sensor (15) with its base on the contact surface of a conductor track of the circuit board (18) sits in contact with a wiring section (18 a ) lengthened in the longitudinal direction over the ceramic body (15), that the two side flanks (15a, 15b) of the ceramic body are covered by insulating strips (17) and that around the outer lateral surfaces of the ceramic body and the circuit board, the metal foil (19), in particular a copper foil, laid around or wrapped around. 7. Pickup according to one of claims 1 to 6, characterized by the fact that the sensor-circuit board combination is received by a lower section (22U) of U-shaped metallic housing, with the inner surfaces of the metal foil (19) is contacted so that metal foil (19) and lower housing part (22U) form the mass. 8. Pickup according to claim 4 or 5, characterized by the fact that a JFET transistor is arranged on the wiring section (18a) of the circuit board (18). 9. Pickup according to one of claims 4, 5 or 8, characterized gekennz ei chn et that the transistor (16T) in a silicone bed (24) is arranged floating and for this purpose its ground line (S) and its signal output -Line (D) are laid with a shape and excess length that enable elastic dodging. 10. Pickup according to claim 7, characterized by zeic hn et that protruding from the U-shaped metallic housing lower part (22U) parts of the sensor-board combination a matching, also U-shaped and metallic housing upper part (220) is slipped and the gap (23) between the two housing parts, for example is bridged by soft soldering, for which purpose the two housing parts (22U, 220) made of a solderable metal alloy, e.g. Nickel silver, exist. 1 1. Pickup according to one of claims 1 to 10, dadurc h gekennzei c hn et that it is glued to the Resonanzköφerwand by means of double-sided adhesive tape (25). 12. Pickup according to claim 11, characterized in that an elastically deformable acrylate adhesive is used as the adhesive material. 13 pickup according to claim 1 or one of claims 4 to 12, characterized g e - indicates that it on the ceiling of a string instrument, for. B. in the form of violin, viola, cello or double bass, is coupled to transmit vibrations. 14. Pickup according to claim 1 or one of claims 4 to 12, characterized in that it is connected to the resonance body wall of a piano or a grand piano in a vibration-transmitting manner. 15. Pickup according to claim 1 or one of claims 4bisl2, characterized in that it on the ceiling of a stringed instrument, for. B. is coupled in the form of banjo, balalaika or mandolin, vibration transmitting. 16. Pickup according to one of claims 1 to 3, characterized in that it (TAl ') has a round or elliptical basic shape and accordingly the piezo sensor (15'), the insulating strips for its flanks, the metal foil, the circuit board (18th ) are adapted to the circular or elliptical layout with their protruding wiring section as well as the lower and upper parts of the housing. 17. Use of piezo-ceramic sensors, piezo-film sensors, piezo-polymer sensors or back electret sensors for the piezo sensor according to one of claims 1 to 16.